You may be preparing your email campaigns for one-off campaigns, for scheduling or for your automated campaigns.
It is a good strategy to right click on each image box to find out the available size before bringing in your images in the correct size, ratio/proportion.
1. When using Mozilla Firefox just right click over the image box and select "View Image Info", then look to the left to view the image box size in pixels.
2. When using Chrome just right click over the image box then select "inspect element", use the scroll bar on the extreme right to scroll down to the bottom where you will see the image box dimensions.
If you have any further questions about images please search our Support website and/or raise a support ticket to us.